Laser-beam reflection for steel stress-strain characterization

Optical methods had been used widely to measure stress-strain by different contact and non-contact methods. This paper introduces an alternative non-contact method to measure the stress-strain evolution based in one laser-beam reflected in the cross-section of a ductile material while it is under a compression load. We use Gaussian beam propagation equations to calculate the area of the reflected beam and we analyse this area increment applying Digital Image Processing. From this calculation we got a stress-strain diagram and we compare it with the real diagram.